scsi_print_msg() is an SPI-specific concept.  This patch moves it from
constants.c to scsi_transport_spi.c and updates the Kconfig to link in
the SPI class for the drivers which use scsi_print_msg().
Signed-off-by: NMatthew Wilcox <matthew@wil.cx>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>